1. Field of the Invention
The present invention relates to a surface modifying material for forming a surface modifying layer provided between a substrate and a resist film, a method of forming a resist pattern using the surface modifying material, and a method of forming a pattern which includes a step for conducting an etching treatment.
Priority is claimed on Japanese Patent Application No. 2010-064365, filed Mar. 19, 2010, the content of which is incorporated herein by reference.
2. Description of the Related Art
In lithography techniques, for example, a resist film composed of a resist material is formed on a substrate, and the resist film is subjected to selective exposure of radial rays such as light or electron beam through a mask having a predetermined pattern, followed by development, thereby forming a resist pattern having a predetermined shape on the resist film. Further, the substrate having the resist pattern formed thereon is then subjected to an etching treatment using the resist pattern as a mask, thereby forming a pattern.
A resist material in which the exposed portions become soluble in a developing solution is called a positive-type, and a resist material in which the exposed portions become insoluble in a developing solution is called a negative-type.
In recent years, in the production of semiconductor elements and liquid crystal display elements, advances in lithography techniques have lead to rapid progress in the field of pattern miniaturization. Typically, these miniaturization techniques involve shortening the wavelength (energy increasing) of the exposure light source. Conventionally, ultraviolet radiation typified by g-line and i-line radiation has been used, but nowadays KrF excimer lasers and ArF excimer lasers are now starting to be introduced in mass production. Furthermore, research is also being conducted into lithography techniques that use an exposure light source having a shorter wavelength (higher energy) than these excimer lasers, such as an electron beam (EB), extreme ultraviolet radiation (EUV), and X ray.
As shortening of the wavelength of the exposure light source progresses, it is required to improve various lithography properties of the resist material, such as the sensitivity to the exposure light source and the resolution capable of reproducing patterns of minute dimensions. As a resist material which satisfies these conditions, a chemically amplified resist has been known. As a chemically amplified composition, a composition including a base component that exhibits a changed solubility in an alkali developing solution under the action of acid and an acid-generator component that generates acid upon exposure is generally used. For example, in a chemically amplified positive resist composition, a base component that exhibits increased solubility in an alkali developing solution under the action of acid is used.
Conventionally, a resin (base resin) is typically used as the base component of a chemically amplified resist composition. In the case of a positive type, a resin that exhibits increased solubility in an alkali developing solution under the action of acid is used as a base resin.
Currently, resins that contain structural units derived from (meth)acrylate esters within the main chain (acrylic resins) are mainly used as base resins for chemically amplified resist compositions that use ArF excimer laser lithography, as they exhibit excellent transparency in the vicinity of 193 nm (for example, see Patent Document 1).
Here, in the present descriptions, the term “(meth)acrylic acid” is a generic term that includes either or both of acrylic acid having a hydrogen atom bonded to the α-position and methacrylic acid having a methyl group bonded to the α-position. The term “(meth)acrylate ester” is a generic term that includes either or both of the acrylate ester having a hydrogen atom bonded to the α-position and the methacrylate ester having a methyl group bonded to the α-position. The term “(meth)acrylate” is a generic term that includes either or both of the acrylate having a hydrogen atom bonded to the α-position and the methacrylate having a methyl group bonded to the α-position.
Further, in order to improve the pattern resolution, a method of forming a pattern has been proposed, in which separation of the resist pattern from the substrate has been suppressed. More specifically, the method of forming a pattern that includes: formation of a thin film (surface modifying layer) of about 10 Å by using a solution prepared by dissolving an epoxylated 1,2-polybutadiene obtained through epoxylation of 1,2-polybutadiene (having a weight average molecular weight of about 150,000) in an organic solvent, and applying the solution onto a silicon wafer; a bake treatment at 130° C.; subsequent formation of a resist pattern (having a line width of 1,000 to 1,500 nm) on top of the silicon wafer onto which the surface modifying layer has been formed; followed by an etching treatment, has been proposed (see Patent Document 2).
[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2003-241385
[Patent Document 2] Japanese Unexamined Patent Application, First Publication No. Sho 56-16129